The Core for Molecular Analysis assists Center investigators in two ways. The first is to guide their planning of projects requiring molecular identification or structural characterization. This may involve mass spectrometric techniques, spectrophotometry or a combination of the two. Investigators receive assistance in the formulation of suitable experimental protocols and in the interpretation of the data obtained. Secondly, the Core supports those portions of the research program in the Liver Center that require experimental characterization of the structure of unknown or covalently modified biomolecular substances. Such investigations may involve either qualitative or quantitative characterization of particular components of complex mixtures isolated from biological sources. It is anticipated for the next period of funding that demand for protein identification will increase significantly and will include de novo sequence determination at the femtomole level. There will also be an increased demand for identification of covalent modifications of proteins both posttranslational and chemical (e.g., xenobiotic-protein adducts) by mass spectrometric methods.